Keeping the electricity grid’s frequency stable is a complex balancing act. For generators to safely run, Australia’s grid frequency needs to stay as close as possible to 50Hz. Any deviation away from this can have catastrophic consequences, like the state-wide power outages in South Australia in 2016.
To help the National Electricity Market (NEM) maintain system security and keep the grid balanced, the Australian Energy Market Operator (AEMO) runs ancillary services markets to procure energy reserves capable of rebalancing the system when it deviates from 50Hz. These are known as the Frequency Control Ancillary Services (FCAS) markets, or what we call frequency control.
When power plants or network lines unexpectedly fail, FCAS brings the grid back into the safe frequency range by balancing demand and supply, which helps to prevent widespread blackouts and outages.